The submarines of the Kaichu III sub-class were a slightly improved version of the preceding Kaichu II subclass, the man difference being an increase in diving depth from 30 to 45.7 meters (98 to 150 ft).^[1] They displaced 752 tonnes (740 long tons) surfaced and 1,013 tonnes (997 long tons) submerged. The submarines were 70.10 meters (230 ft 0 in) long and had a beam of 6.12 meters (20 ft 1 in) and a draft of 3.70 meters (12 ft 2 in).

For surface running, the submarines were powered by two 1,450-brake-horsepower (1,081 kW) Sulzer Mark II diesel engines, each driving one propeller shaft. When submerged each propeller was driven by a 600-horsepower (447 kW) electric motor. They could reach 16.5 knots (31 km/h; 19 mph) on the surface and 8.5 knots (15.7 km/h; 9.8 mph) underwater. On the surface, they had a range of 6,000 nautical miles (11,000 km; 6,900 mi) at 10 knots (19 km/h; 12 mph); submerged, they had a range of 85 nmi (157 km; 98 mi) at 4 knots (7.4 km/h; 4.6 mph).

The submarines were armed with six 450 mm (18 in) torpedo tubes, four internal tubes in the bow and two external tubes mounted on the upper deck, and carried a total of ten Type 44 torpedoes. They were also armed with a single 76.2 mm (3.00 in) deck gun mounted aft of the conning tower.^[1]

Ro-24 was laid down as Submarine No. 42 on 21 April 1919 by the Sasebo Naval Arsenal at Sasebo, Japan.^[2] Launched on 8 December 1919,^[2] she was completed and commissioned on 30 November 1920^[2] as the first until of the Kaichu III subclass.

Upon commissioning, Submarine No. 42 was attached to the Sasebo Naval District, to which she remained attached throughout her career.^[2] On 15 December 1921, she was assigned to Submarine Division 22 and to the Mako Defense Division at Mako in the Pescadores Islands.^[2] On 1 December 1922, Submarine Division 22 was reassigned to the Sasebo Defense Division,^[2] and on 1 November 1924, Submarine No. 42 was renamed Ro-24.^[2] On 1 December 1924, Submarine Division 22 was reassigned to the Chinkai Defense Division on the southern coast of Chōsen.^[2] Submarine Division 22 returned to the Sasebo Defense Division on 1 December 1925, serving in it until 15 November 1934,^[2] and thereafter operated directly under the control of the Sasebo Naval District.^[2]

Ro-24 was stricken from the Navy list on 1 April 1935.^[2] She was hulked on 7 August 1935 and renamed Hulk No. 3107.^[2]

• "Rekishi Gunzō"., History of Pacific War Vol.17 I-Gō Submarines, Gakken (Japan), January 1998, ISBN 4-05-601767-0
• Rekishi Gunzō, History of Pacific War Extra, "Perfect guide, The submarines of the Imperial Japanese Forces", Gakken (Japan), March 2005, ISBN 4-05-603890-2
• The Maru Special, Japanese Naval Vessels No.43 Japanese Submarines III, Ushio Shobō (Japan), September 1980, Book code 68343-44
• The Maru Special, Japanese Naval Vessels No.132 Japanese Submarines I "Revised edition", Ushio Shobō (Japan), February 1988, Book code 68344-36
• The Maru Special, Japanese Naval Vessels No.133 Japanese Submarines II "Revised edition", Ushio Shobō (Japan), March 1988, Book code 68344-37
• The Maru Special, Japanese Naval Vessels No.135 Japanese Submarines IV, Ushio Shobō (Japan), May 1988, Book code 68344-39